Colin FosterBy Colin Foster

Updated November 2026

An outdoor products hiking backpack is a pack built for multi-hour walking with gear on your back, and the right one depends on three things: torso length, trip length and how you plan to carry your load. Start by measuring your torso, then match a pack volume to your typical trip. Most day hikers do well with 20 to 30 liters, while overnight trips usually call for 40 to 60 liters.

Why Fit Matters More Than Brand

A backpack that fits poorly will cause shoulder fatigue, hip pain and rubbing well before the trail gets hard. Fit is driven mainly by torso length, not height. Many packs come in multiple torso sizes, and manufacturers usually specify the measurement range each size covers. If the hipbelt sits above your iliac crest or the shoulder straps pull away from your shoulders, the pack is the wrong size even if the volume looks right.

Shopping for one? See our guide: 4 Best Hiking Backpack Women's (2026): Expert Picks.

Factors That Change Your Choice

Once fit is settled, look at these details:

  • Volume: Day packs run roughly 15 to 30 liters. Multi-day packs run 40 to 70 liters. Bigger is not better if it tempts you to carry extra weight.
  • Frame type: Internal frames suit most trail use. External frames carry heavy, bulky loads more comfortably but are less stable on rough ground.
  • Weather protection: If you hike in rain or snow, check whether the fabric is coated or whether the pack includes a rain cover. For a deeper look, see Waterproof Backpack for Hiking: How to Choose One That Keeps Gear Dry.
  • Weight: Ultralight packs save ounces but often have thinner fabric and less padding. Weigh the pack empty and decide whether the savings are worth the trade-off.

Practical Steps to Choose and Load Your Pack

  1. Measure your torso from the C7 vertebra (the bony bump at the base of your neck) down to the top of your hip bones.
  2. Pick a volume based on your longest typical trip, not your ideal one.
  3. Try the pack with weight in it. Ask a shop to load it with 15 to 20 pounds if you can.
  4. Tighten the hipbelt first so it carries about 80 percent of the load, then adjust the shoulder straps.
  5. Pack heavy items close to your back and between your shoulder blades, with lighter, bulkier items toward the outside.
  6. Use a pack liner or dry bags for anything that must stay dry, since outer fabric alone rarely keeps water out in heavy rain.

If you are comparing sizing systems in more depth, the guide to Mystery Ranch Hiking Backpack Guide: Sizing, Fit and Packing Tips walks through torso measurement in detail. For multi-day planning, Multi Day Hiking Backpack: How to Choose One for 3–7 Day Trips covers volume choices for longer routes.

What We’d Use

For a general-purpose trail pack with an internal frame and an adjustable torso, the Osprey Talon 22 is a widely recommended option for day hikes. View on Amazon

For longer overnight trips, the Osprey Atmos AG 65 is a common choice because its suspension system is designed to carry heavier loads. View on Amazon

FAQ

What size hiking backpack do I need for a day hike?

Most day hikes are well served by a pack between 20 and 30 liters. That volume holds water, a layer, food and a first aid kit without encouraging you to overpack.

Should I choose an internal or external frame?

Internal frames suit most hikers and most trails. External frames can be better for heavy loads on smooth terrain, but they are less agile on steep or uneven ground.

How do I know if a hiking backpack fits?

A well-fitting pack carries most of its weight on your hips, not your shoulders. The shoulder straps should sit snugly without pulling, and the hipbelt should wrap your hip bones. If you are unsure, consult a professional fitter at an outdoor retailer before buying.

Ready to choose one?

Colin Foster

About Colin Foster

Colin Foster is part of our editorial team and reviews and edits our backpacks & packing systems guides, checking product details against manufacturer specifications and owner feedback.